Hoisting ropes typically include one or several load bearing members that are elongated in the longitudinal direction of the rope and each form a structure that continues unbroken throughout the length of the rope. Load bearing members are the members of the rope which are able to bear together the load exerted on the rope in its longitudinal direction. The load, such as a weight suspended by the rope, causes tension on the load bearing member in the longitudinal direction of the rope, which tension can be transmitted by the load bearing member in question all the way from one end of the rope to the other end of the rope. Ropes may further comprise non-bearing components, such as a coating, which cannot transmit tension in the above described way. The coating can be utilized for one or more purposes. For instance, the coating can be used to provide rope with a surface via which the rope can effectively engage frictionally with a drive wheel. The coating can also be used to provide the load bearing members of the rope with protection and/or for separating these from each other.
In a hoisting apparatus, the rope ends need to be fixed to a base, which is typically either the load to be lifted or a stationary structure. In the field of elevators, the rope ends can be fixed directly to the load, such as the car or counterweight, which is the case when these are to be suspended with 1:1 ratio. Alternatively, the rope ends can be fixed to a stationary structure of the building, which is the case when the car and counterweight are to be suspended with 2:1 ratio, for instance. In prior art, hoisting ropes have been fixed to the base with a rope terminal assembly.
In prior art such a rope terminal assembly has been proposed where the rope end is compressed in a nip formed between two compression members. This kind of configuration relies largely on the grip produced by the compression. The compression may be provided by a wedge-type structure, for instance, where wedging movement of wedge components in a rope terminal housing produces said compression. With this kind of configuration, the drawback is that when used with ropes that comprise a coating, the gripping ability may weaken in conditions which change the properties of the coating. As a result, the terminal assembly might malfunction such that the grip is not reliable any more. For example, as a result of exposure to extreme conditions, the coating may soften and ultimately melt. Said drawbacks have been noticed to be present particularly when the coating is made of thermoplastic material, and due to some abnormal event the rope terminal is exposed to high temperatures. Then the thermoplastic material gets softer and eventually melts. At the same time, compression is applied against the coating, so the coating material starts to be displaced pushed by the compression. In this kind of situation, problems in performance of the rope terminal assembly could be likely to cause some sort of malfunction. Problems could be caused also due to some of the coating being displaced into small gaps between the movable parts of the terminal assembly, such as between a housing and the wedge, such that proper relative movement between these two would be blocked. This would make their later operation unreliable. Great amount of melted coating material can also decrease friction between the rope and the compression member, working like a lubricant contributing to slipping of the rope away from the terminal assembly. In the worst case, the rope might slide away from the rope terminal.